AD AD8216YRZ

High Bandwidth, Bidirectional
65 V Difference Amplifier
AD8216
±4000 V HBM ESD
Ideal for current shunt applications
High common-mode voltage range
−4 V to +65 V operating
−40 V to +80 V survival
3 MHz bandwidth
<100 ns output propagation delay
Gain: 3 V/V
Wide operating temperature range
Die: −40°C to +150°C
8-lead SOIC: −40°C to +125°C
Adjustable output offset
Available in 8-lead SOIC
Excellent ac and dc performance
10 μV/°C offset drift
10 ppm/°C gain drift
FUNCTIONAL BLOCK DIAGRAM
V+
6
+IN 8
5
OUT
7
VREF 1
3
VREF 2
–IN 1
AD8216
NC 4
2
NC = NO CONNECT
GND
07062-001
FEATURES
Figure 1.
APPLICATIONS
High-side current sensing in
DC-to-dc converters
Motor controls
Transmission controls
Diesel-injection controls
Engine management
Suspension controls
Vehicle dynamic controls
GENERAL DESCRIPTION
The AD8216 is a single-supply, difference amplifier ideal for
amplifying small differential voltages in the presence of large
common-mode voltages. The operating input common-mode
voltage range extends from −4 V to +65 V. The typical supply
voltage is 5 V. The AD8216 features a 3 MHz bandwidth,
allowing for the input-to-output propagation delay that is
always less than 150 ns. This feature is ideal for applications
monitoring rapidly increasing and decreasing load currents.
The AD8216 is offered in a SOIC package. The operating
temperature range is −40°C to +125°C.
Excellent ac and dc performance over temperature keep errors
in the measurement loop to a minimum. Offset and gain drift
are guaranteed to a maximum of 20 μV/°C and 15 ppm/°C,
respectively.
The output offset can be adjusted from 0.06 V to 4.9 V with a
5 V supply by using the VREF1 pin and the VREF2 pin. With the
VREF1 pin attached to the V+ pin and the VREF2 pin attached to
the GND pin, the output is set at half scale. Attaching both VREF1
and VREF2 to GND causes the output to be unipolar, starting
near ground. Attaching both VREF1 and VREF2 to V+ causes the
output to be unipolar, starting near V+. Other offsets can be
obtained by applying an external voltage to VREF1 and VREF2.
Rev. 0
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other
rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarks and registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
www.analog.com
Fax: 781.461.3113
©2007 Analog Devices, Inc. All rights reserved.
AD8216
TABLE OF CONTENTS
Features .............................................................................................. 1
Ground Referenced Output ...................................................... 11
Applications....................................................................................... 1
V+ Referenced Output .............................................................. 11
Functional Block Diagram .............................................................. 1
Bidirectional Operation............................................................. 11
General Description ......................................................................... 1
External ReferenceD Output .................................................... 12
Revision History ............................................................................... 2
Splitting the Supply .................................................................... 12
Specifications..................................................................................... 3
Splitting an External Reference ................................................ 12
Absolute Maximum Ratings............................................................ 4
Applications Information .............................................................. 13
ESD Caution.................................................................................. 4
High-Side Current Sense with a Low-Side Switch................. 13
Pin Configuration and Function Descriptions............................. 5
High-Side Current Sense with a High-Side Switch ............... 13
Typical Performance Characteristics ............................................. 6
Outline Dimensions ....................................................................... 14
Theory of Operation ...................................................................... 10
Ordering Guide .......................................................................... 14
Output Offset Adjustment............................................................. 11
Unidirectional Operation.......................................................... 11
REVISION HISTORY
11/07—Revision 0: Initial Version
Rev. 0 | Page 2 of 16
AD8216
SPECIFICATIONS
TA = operating temperature range, VS = 5 V, unless otherwise noted.
Table 1.
Parameter
GAIN
Initial
Accuracy
Accuracy Over Temperature
Gain vs. Temperature
VOLTAGE OFFSET
Offset Voltage, RTI
Over Temperature, RTI
Offset Drift
INPUT
Input Impedance
Differential
Common Mode
Input Voltage Range
Common-Mode Rejection
OUTPUT
Output Voltage Range
Output Resistance
DYNAMIC RESPONSE
Small Signal −3 dB Bandwidth
Slew Rate
Propagation Delay
NOISE
0.1 Hz to 10 Hz, RTI
Spectral Density, 1 kHz, RTI
OFFSET ADJUSTMENT
Ratiometric Accuracy 2
Accuracy, RTO
Output Offset Adjustment Range
VREF Input Voltage Range
VREF Divider Resistor Values
POWER SUPPLY
Operating Range
Quiescent Current Over Temperature
Power Supply Rejection Ratio
TEMPERATURE RANGE
For Specified Performance
1
2
Conditions
Min
Typ
Max
Unit
±0.25
±0.4
15
V/V
%
%
ppm/°C
±3
±20
mV
mV
μV/°C
3
VOUT ≥ 0.1 V dc, 25°C
Specified temperature range
10
25°C
Specified temperature range
±0.5
±10
400
200
Common mode, continuous
Differential, VREF1 and VREF2 tied to GND
Differential, VREF1 @ GND and VREF2 @ 5 V
25°C, f = dc to 20 kHz 1
Operating temperature range, f = dc to 20 kHz1
−4
−800
80
80
RL = 25 kΩ
0.06
+65
1.6
Input-to-output response
+800
90
90
4.9
200
V
Ω
3
15
100
MHz
V/μs
ns
150
20
0.5
Divider to supplies
Voltage applied to VREF1 and VREF2 in parallel
VS = 5 V
0.499
0.06
0.0
24
μV p-p
μV/√Hz
32
0.501
±0.5
4.9
VS
40
V/V
mV/V
V
V
kΩ
1
5.5
2
V
mA
dB
+125
°C
4.5
VOUT = 0.1 V dc
70
Operating temperature range
Source imbalance < 2 Ω.
The offset adjustment is ratiometric to the power supply when VREF1 and VREF2 are used as a divider between the supplies.
Rev. 0 | Page 3 of 16
−40
kΩ
kΩ
V
V
mV
dB
dB
AD8216
ABSOLUTE MAXIMUM RATINGS
Table 2.
Parameter
Supply Voltage
Continuous Input Common-Mode Voltage
Continuous Input Differential Voltage
Reverse Supply Voltage
ESD Rating
HBM (Human Body Model)
CDM (Charged Device Model)
Operating Temperature Range
Storage Temperature Range
Output Short-Circuit Duration
ESD CAUTION
Rating
12.5 V
−40 V to +80 V
6V
0.3 V
±4000 V
±1000 V
−40°C to +125°C
−65°C to +150°C
Indefinite
Stresses above those listed under Absolute Maximum Ratings
may cause permanent damage to the device. This is a stress
rating only and functional operation of the device at these or
any other conditions above those indicated in the operational
section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability.
Rev. 0 | Page 4 of 16
AD8216
1
–IN 1
8
GND 2
VREF 2 3
NC 4
7
AD8216
TOP VIEW
(Not to Scale)
8
+IN
7
VREF 1
6
V+
5
OUT
2
NC = NO CONNECT
6
5
Figure 3. Pin Configuration
07062-002
3
07062-003
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
Figure 2. Metallization Diagram
Table 3. Pin Function Descriptions
Pin No.
1
2
3
4
5
6
7
8
Mnemonic
−IN
GND
VREF2
NC
OUT
V+
VREF1
+IN
X
−320
−357
−349
NC
+348
+349
+349
+318
Y
+390
+14
−201
NC
−325
−194
−26
+390
Die size is 1100 μm by 1035 μm.
Die thickness is 13 mil.
Minimum passivation opening (minimum bond pad size)
is 92 μm × 92 μm.
Passivation type is 8 kA USG (Oxide) + 10 kA Oxynitride.
Bond pad metal composition is 98.5% Al, 1% Si, and 0.5% Cu.
Backside potential is V+.
Rev. 0 | Page 5 of 16
AD8216
500
400
300
100
GAIN (dB)
VOSI (µV)
200
0
–100
–200
–300
–500
–40
–20
0
20
40
60
80
100
120
TEMPERATURE (°C)
07062-016
–400
20
15
10
5
0
–5
–10
–15
–20
–25
–30
–35
–40
–45
–50
–55
–60
1k
10k
100k
07062-015
TYPICAL PERFORMANCE CHARACTERISTICS
1M
FREQUENCY (Hz)
Figure 4. Typical Offset Drift
Figure 7. Typical Small Signal Bandwidth (VOUT = 200 mV p-p)
120
110
INPUT (200mV/DIV)
100
90
CMRR (dB)
80
70
60
OUTPUT (500mV/DIV)
50
40
30
20
100
1k
10k
100k
1M
10M
100M
FREQUENCY (Hz)
Figure 5. CMRR vs. Frequency
TIME (200ns/DIV)
07062-011
0
10
07062-021
10
Figure 8. Rise Time
1500
1300
1100
900
500
INPUT (200mV/DIV)
300
100
–100
–300
–500
–700
–900
OUTPUT (500mV/DIV)
–1100
–1500
–40
–20
0
20
40
60
TEMPERATURE (°C)
80
100
120
TIME (200ns/DIV)
Figure 6. Typical Gain Drift
Figure 9. Fall Time
Rev. 0 | Page 6 of 16
07062-010
–1300
07062-017
GAIN ERROR (ppm)
700
INPUT (1V/DIV)
OUTPUT (2V/DIV)
8
6
4
2
0
–40
07062-008
TIME (500ns/DIV)
10
–20
0
20
40
60
80
100
120
140
TEMPERATURE (°C)
07062-019
MAXIMUM OUTPUT SOURCE CURRENT (mA)
AD8216
Figure 13. Maximum Output Source Current vs. Temperature
Figure 10. Differential Overload Recovery (Falling)
OUTPUT VOLTAGE RANGE (V)
5.0
INPUT (1V/DIV)
3.5
3.0
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
OUTPUT SOURCE CURRENT (mA)
07062-007
2.0
07062-009
TIME (500ns/DIV)
Figure 14. Output Voltage Range vs. Output Source Current
Figure 11. Differential Overload Recovery (Rising)
2.5
7
6
5
4
3
2
–20
0
20
40
60
80
100
120
140
TEMPERATURE (°C)
1.5
1.0
0.5
0
07062-020
1
2.0
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
OUTPUT SINK CURRENT (mA)
Figure 15. Output Voltage Range from GND vs. Output Sink Current
Figure 12. Maximum Output Sink Current vs. Temperature
Rev. 0 | Page 7 of 16
07062-006
OUTPUT VOLTAGE RANGE FROM GND (V)
8
MAXIMUM OUTPUT SINK CURRENT (mA)
4.0
2.5
OUTPUT (2V/DIV)
0
–40
4.5
AD8216
700
PROPAGATION
DELAY
85ns
500
400
INPUT (50mV/DIV)
ZERO CROSSING
300
200
OUTPUT (50mV/DIV)
100
0
5
10
15
20
25
30
35
40
45
50
55
60
65
INPUT COMMON-MODE VOLTAGE (V)
AX
AY
07062-014
0
BY
TIME (50ns/DIV)
Figure 16. Total Input Bias Current vs. Input Common-Mode Voltage
07062-013
TOTAL INPUT BIAS CURRENT (µA)
BX
600
Figure 19. Propagation Delay (Falling)
7
AX
OUTPUT ERROR (%)
6
PROPAGATION
DELAY
110ns
5
4
INPUT (50mV/DIV)
3
ZERO CROSSING
2
1
07062-018
0
0.01 0.04 0.07 0.10 0.13 0.16 0.19 0.22 0.25 0.28 0.31 0.34 0.37 1.60
DIFFERENTIAL INPUT (V)
BX
BY
TIME (50ns/DIV)
Figure 17. Output Error (%) vs. Differential Input Voltage
(Unidirectional Operation (VREF1 and VREF2 Connected to GND))
07062-012
OUTPUT (50mV/DIV)
AY
Figure 20. Propagation Delay (Rising)
1.0
8000
0.6
0.4
6000
COUNT
0.2
0
4000
–0.2
–0.4
–0.8
–1.0
–1.0
–0.8
–0.6
–0.4
–0.2
0
0.2
0.4
0.6
0.8
0
–15
1.0
07062-037
2000
–0.6
07062-039
TOTAL OUTPUT ERROR (%)
0.8
–10
–5
OFFSET DRIFT (ppm/°C)
INPUT DIFFERENTIAL VOLTAGE (V)
Figure 21. Gain Drift Distribution
Figure 18. Output Error (%) vs. Differential Input Voltage
(Bidirectional Operation (VREF1 and VREF2 Connected to 2.5 V))
Rev. 0 | Page 8 of 16
0
5
AD8216
800
700
500
400
300
200
07062-038
COUNT
600
100
0
–20
–10
0
10
20
OFFSET DRIFT (µV/°C)
Figure 22. Offset Drift Distribution
Rev. 0 | Page 9 of 16
AD8216
THEORY OF OPERATION
The AD8216 is a single-supply difference amplifier typically used
to accurately amplify a small differential current shunt voltage in
the presence of a rapidly changing common-mode voltage.
The AD8216 consists of an amplifier (A1), a resistor network,
a small voltage reference, and a bias circuit (not shown),
see Figure 23.
The reference inputs, VREF1 and VREF2, are tied through resistors
to the positive input of A1, which allows the output offset to be
adjusted anywhere in the output operating range. The gain is
1 V/V from the reference pins to the output when the reference
pins are used in parallel. When they are used to divide the supply,
the gain is 0.5 V/V.
The ratios of RA, RB, RC, and RF are trimmed to a high level of
precision to allow the CMRR to exceed 80 dB. This performance is
accomplished by laser trimming the resistor ratio matching to
better than 0.01%.
B
B
The input resistor network also attenuates normal (differential)
mode voltages. Therefore, Amplifier A1 features a gain of
54 V/V to provide a total system gain of 3V/V.
Total Gain (V/V) = 1/18 (V/V) × 54 (V/V) = 3 V/V
–IN
RA
+IN
RA
A1
RB
RB
VOUT
RF
VREF1
RREF
RC
RREF
RC
VREF2
250mV
AD8216
GND
Figure 23. Simplified Schematic
Rev. 0 | Page 10 of 16
07062-028
The set of input attenuators preceding A1 consist of RA, RB, and
RC, which feature a combined series resistance of approximately
200 kΩ ± 20%. The purpose of these resistors is to attenuate the
input voltage to match the input voltage range of A1. This
balanced resistor network attenuates the common-mode signal
by a ratio of 1/18. A1 amplifier inputs are held within the power
supply range, even if Pin 1 and Pin 8 exceed the supply or fall
below common (ground). A reference voltage of 250 mV biases
the attenuator above ground, which allows the amplifier to
operate in the presence of negative common-mode voltages.
AD8216
OUTPUT OFFSET ADJUSTMENT
The output of the AD8216 can be adjusted for unidirectional or
bidirectional operation.
UNIDIRECTIONAL OPERATION
Unidirectional operation allows the AD8216 to measure currents
through a resistive shunt in one direction. The basic modes for
unidirectional operation are ground referenced output mode
and V+ referenced output mode.
V+ REFERENCED OUTPUT
The V+ referenced output mode is set when both reference
pins are tied to the positive supply. It is typically used when the
diagnostic scheme requires detection of the amplifier and the
wiring before power is applied to the load (see Figure 25).
V+
+IN
For unidirectional operation, the output can be set at the
negative rail (near ground) or at the positive rail (near V+)
when the differential input is 0 V. The output moves to the
opposite rail when a correct polarity differential input voltage is
applied. In this case, full scale is approximately 1.6 V. The required
polarity of the differential input depends on the output voltage
setting. If the output is set at the positive rail, the input polarity
needs to be negative to move the output down. If the output is
set at ground, the polarity is positive to move the output up.
OUT
–IN
VREF 1
AD8216
NC
VREF 2
GND
07062-030
NC = NO CONNECT
GROUND REFERENCED OUTPUT
When using the AD8216 in this mode, both referenced inputs are
tied to ground, which causes the output to sit at the negative rail
when there are zero differential volts at the input (see Figure 24).
Figure 25. V+ Referenced Output
Table 5. V+ = 5 V
VIN (Referred to −IN)
0V
−1.6 V
VOUT
4.9 V
0.1 V
V+
+IN
BIDIRECTIONAL OPERATION
OUT
–IN
Bidirectional operation allows the AD8216 to measure currents
through a resistive shunt in two directions.
VREF 1
AD8216
NC
In this case, the output is set anywhere within the output range.
Typically, it is set at half scale for equal range in both directions.
In some cases, however, it is set at a voltage other than half scale
when the bidirectional current is nonsymmetrical.
VREF 2
GND
07062-029
NC = NO CONNECT
Figure 24. Ground Referenced Output
Table 4. V+ = 5 V
VIN (Referred to −IN)
0V
1.6 V
VOUT
0.06 V
4.8 V
Table 6. V+ = 5 V, VOUT = 2.5 V with VIN = 0 V
VIN (Referred to −IN)
+800 mV
−800 mV
VOUT
4.9 V
0.1V
Adjusting the output is accomplished by applying voltage(s) to
the referenced inputs.
VREF1 and VREF2 are tied to internal resistors that connect to an
internal offset node. There is no operational difference between
the pins.
Rev. 0 | Page 11 of 16
AD8216
EXTERNAL REFERENCED OUTPUT
Tying both pins together and to a reference produces an output
equal to the reference voltage when there is no differential input
(see Figure 26). The output moves down from the reference
voltage when the input is negative, relative to the −IN pin, and
up when the input is positive, relative to the −IN pin.
V+
+IN
OUT
–IN
VREF 1
AD8216
V+
+IN
NC
OUT
VREF 2
GND
07062-032
–IN
NC = NO CONNECT
VREF 1
AD8216
Figure 27. Split Supply
2.5V VOLTAGE
REFERENCE
SPLITTING AN EXTERNAL REFERENCE
NC
VREF 2
07062-031
GND
NC = NO CONNECT
In this case, an external reference is divided by 2 with an
accuracy of approximately 0.5% by connecting one VREF pin to
ground and the other VREF pin to the reference (see Figure 28).
Figure 26. External Referenced Output
V+
SPLITTING THE SUPPLY
+IN
By tying one reference pin to V+ and the other to the ground
pin, the output is set at half of the supply when there is no
differential input (see Figure 27). The benefit is that no external
reference is required to offset the output for bidirectional current
measurement. This configuration creates a midscale offset that is
ratiometric to the supply, which means that if the supply increases
or decreases, the output remains at half the supply. For example, if
the supply is 5.0 V, the output is at half scale or 2.5 V. If the supply
increases by 10% (to 5.5 V), the output goes to 2.75 V.
–IN
OUT
VREF 1
AD8216
5V
NC
VREF 2
NC = NO CONNECT
07062-033
GND
Figure 28. Split External Reference
Rev. 0 | Page 12 of 16
VOLTAGE
REFERENCE
AD8216
APPLICATIONS INFORMATION
A typical application for the AD8216 is high-side measurement
of a current through a solenoid for PWM control of the solenoid
opening. Typical applications include dc-to-dc converters,
motor controls, and solenoid controls.
Two typical circuit configurations are used for this type of
application.
When using a high-side switch, the battery voltage is connected
to the load when the switch is closed, causing the commonmode voltage to increase to the battery voltage. In this case,
when the switch is opened, the voltage reversal across the
inductive load causes the common-mode voltage to be held
one diode drop below ground by the clamp diode.
5V
HIGH-SIDE CURRENT SENSE WITH A LOW-SIDE
SWITCH
SWITCH
In this case, the PWM control switch is ground referenced. An
inductive load (solenoid) is tied to a power supply. A resistive
shunt is placed between the switch and the load (see Figure 29).
An advantage of placing the shunt on the high side is that the
entire current, including the recirculation current, can be
measured because the shunt remains in the loop when the
switch is off. In addition, diagnostics can be enhanced because
shorts to ground can be detected with the shunt on the high side.
42V
BATTERY
+IN VREF 1 V+
OUT
AD8216
SHUNT
–IN
GND VREF 2 NC
CLAMP
DIODE
NC = NO CONNECT
07062-035
INDUCTIVE
LOAD
Figure 30. High-Side Switch
In this circuit configuration, when the switch is closed, the
common-mode voltage moves down to near the negative rail.
When the switch is opened, the voltage reversal across the
inductive load causes the common-mode voltage to be held
one diode drop above the battery by the clamp diode.
5V
CLAMP
DIODE
42V
BATTERY
INDUCTIVE
LOAD
+IN VREF 1 V+
OUT
The AD8216 measures current in both directions as the H-bridge
switches and the motor changes direction. The output of the
AD8216 is configured in an external reference bidirectional
mode (see the Output Offset Adjustment section).
AD8216
SHUNT
–IN
Another typical application for the AD8216 is as part of the
control loop in H-bridge motor controls. In this case, the AD8216
is placed in the middle of the H-bridge so that it can accurately
measure current in both directions by using the shunt available
at the motor (see Figure 31). This is a better solution than a
ground referenced op amp because ground is not typically a
stable reference voltage in this type of application. This instability
in the ground reference causes the measurements that could be
made with a simple ground referenced op amp to be inaccurate.
GND VREF 2 NC
NC = NO CONNECT
07062-034
SWITCH
CONTROLLER
5V
Figure 29. Low-Side Switch
MOTOR
HIGH-SIDE CURRENT SENSE WITH A HIGH-SIDE
SWITCH
+IN VREF 1 V+
OUT
AD8216
SHUNT
–IN
Rev. 0 | Page 13 of 16
GND VREF 2 NC
5V
2.5V
NC = NO CONNECT
Figure 31. Motor Control Application
07062-036
This configuration minimizes the possibility of unexpected
solenoid activation and excessive corrosion (see Figure 30). In
this case, both the switch and the shunt are on the high side.
When the switch is off, it removes the battery from the load,
which prevents damage from potential shorts to ground, while still
allowing the recirculating current to be measured and providing
for diagnostics. Removing the power supply from the load for
the majority of the time minimizes the corrosive effects that
could be caused by the differential voltage between the load
and ground.
AD8216
OUTLINE DIMENSIONS
5.00 (0.1968)
4.80 (0.1890)
1
5
4
1.27 (0.0500)
BSC
0.25 (0.0098)
0.10 (0.0040)
COPLANARITY
0.10
SEATING
PLANE
6.20 (0.2441)
5.80 (0.2284)
1.75 (0.0688)
1.35 (0.0532)
0.51 (0.0201)
0.31 (0.0122)
0.50 (0.0196)
0.25 (0.0099)
45°
8°
0°
0.25 (0.0098)
0.17 (0.0067)
1.27 (0.0500)
0.40 (0.0157)
COMPLIANT TO JEDEC STANDARDS MS-012-A A
CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS
(IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR
REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN.
012407-A
8
4.00 (0.1574)
3.80 (0.1497)
Figure 32. 8-Lead Standard Small Outline Package [SOIC_N]
Narrow Body (R-8)
Dimensions shown in millimeters and (inches)
ORDERING GUIDE
Model
AD8216YRZ 1
AD8216YRZ-RL1
AD8216YRZ-R71
1
Temperature Range
−40°C to +125°C
−40°C to +125°C
−40°C to +125°C
Package Description
8-Lead SOIC_N
8-Lead SOIC_N, 13” Tape and Reel
8-Lead SOIC_N, 7” Tape and Reel
Z = RoHS Compliant Part.
Rev. 0 | Page 14 of 16
Package Option
R-8
R-8
R-8
AD8216
NOTES
Rev. 0 | Page 15 of 16
AD8216
NOTES
©2007 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D07062-0-11/07(0)
T
T
Rev. 0 | Page 16 of 16